1. Field of the Invention
This invention relates to the field of swimming pools, spas, and fountains. More specifically, the invention comprises a method for sealing the surface of a new or reconditioned masonry structure.
2. Description of the Related Art
Concrete pools have been in common use for many years. These pools are formed as a thin concrete shell (typically 4 to 6 inches thick) surrounded by earth. The shell is typically reinforced by wire mesh or re-bar. Once cured, the inward-facing surface of the concrete shell must be sealed in order to contain the pool water. This sealing is typically accomplished by adding a layer of marcite plaster (masonry plaster) over the concrete.
Those skilled in the art will know that properly adding the marcite layer to a pool is a job requiring some skill. Variations in the thickness of the layer can cause cracking, crazing, or delamination. This step has traditionally been labor-intensive, and represents a significant cost in the construction of a new pool.
FIG. 1 shows a prior art swimming pool 10. The pool is bounded by wall 12 (The term “wall” is intended to include all inward facing surfaces, such as the bottom). It may also feature a decorative tile band 14 near the top. FIG. 2 shows a closer view of wall 12 on a pool that has been in service for a few years. Cracks 14 typically appear in the marcite layer. If a piece of marcite actually breaks away, a void 16 results. Both the cracks and the voids allow the pool water to penetrate to the underlying concrete (The marcite is actually porous, but much less so than the underlying concrete). As the concrete itself is porous, this water leaks out of the pool. The water penetration can also damage the concrete structural shell.
FIG. 3 shows a section through wall 12. A gap in the plaster 22 is labeled as void 16. Water entering this void will seep through the concrete.
Some leakage can be tolerated. However, once a significant number of cracks and voids are present, the pool must be resurfaced. The water is drained, and the old marcite plaster layer is chipped or ground away. After the underlying concrete surface is cleaned and prepared, a new marcite plaster layer is added. The cost of such an operation is substantial. It may also take the pool out of service for many weeks.